1. Field of the Invention
The present invention relates to an apparatus for feeding paper in a stable manner.
2. Description of the Prior Art
As shown in FIGS. 1 and 2, and apparatus for feeding paper which has holes 12 includes a timing belt 2 which is disposed over a driving pulley 3 and a driven pulley 4. The pulleys 3, 4 are mounted on shafts which are fixed to a tractor frame 6, and pins 1 are mounted on the timing belt 2 so that they are not positioned on the outer periphery of the belt 2. The pins 1 fit into the holes 12 of the paper 11 in order to feed the paper 11. However, the feeding of the paper 11 is generally delayed by friction which is generated in the paper path and which is formed by a paper guide 7 and a tractor cover 9. As a result, the pins 1 are pushed inward due to the rigidity of the paper 11 when the pins 1 begin to fit into the holes 12, as shown in FIGS. 3 and 4. Hence, the pins 1 do not fit well into the holes 12, which causes jamming of the paper. Paper jamming creates numerous inconveniences because it is impossible to feed the paper in a stable manner if it constantly jams.
To solve these problems, an apparatus like that disclosed in U. S. Pat. No. 3,606,122, and illustrated generally in FIGS. 5 and 6, has been proposed. In this apparatus, the tractor frame 6 is extended so that it confronts and supports the bottom of the pins 1, as shown in FIG. 6. Accordingly, the tractor frame extension prevents the pins 1 from being pushed inward by the paper 11. The paper 11 is lifted by the reaction force of the pins 1 and regulated by the tractor cover 9 so that the pins 1 fit firmly into the holes 12.
However, because the bottoms of the pins 1 constantly come into contact with the tractor frame 6, a large frictional force is generated between the pin bottoms and the tractor frame 6 so that the pins 1 are delayed with respect to the pitch advance of the holes 12. As a result, the pins 1 eat into portions of the paper 11 other than the holes 2. If the paper 11 is weak-waisted, the paper 11 is torn, thereby making it impossible to feed the paper regularly. If the paper 11 is what is called "multi-paper" or the like, in which a copying paper is inserted between papers, and if the paper is also strong-waisted, should corresponding holes 12 of the paper be misaligned, the pins 1 are unable to fit into the holes 12. This results in a locked state in which the paper 11 floats and idles if the driving force of the tractor is strong.